Include backtrace in error message when LuaErrors occur

Tested in both Lua and LuaJIT by passing (NaN,NaN,NaN) to ObjectRef::setvelocity().

src/script/cpp_api/s_base.cpp

@@ -231,6 +231,11 @@ void ScriptApiBase::stackDump(std::ostream &o)
 	o << std::endl;
 }
 
+std::string ScriptApiBase::getBacktrace()
+{
+	return script_get_backtrace(getStack());
+}
+
 void ScriptApiBase::setOriginDirect(const char *origin)
 {
 	m_last_run_mod = origin ? origin : "??";

src/script/cpp_api/s_base.h

@@ -75,6 +75,7 @@ public:
 	void removeObjectReference(ServerActiveObject *cobj);
 
 	Server* getServer() { return m_server; }
+	std::string getBacktrace();
 
 	std::string getOrigin() { return m_last_run_mod; }
 	void setOriginDirect(const char *origin);

src/server.cpp

@@ -108,7 +108,14 @@ void *ServerThread::run()
 		} catch (con::ConnectionBindFailed &e) {
 			m_server->setAsyncFatalError(e.what());
 		} catch (LuaError &e) {
-			m_server->setAsyncFatalError("Lua: " + std::string(e.what()));
+			std::ostringstream os(std::ios::binary);
+			os<<"Lua: "<<e.what();
+			std::string bt = m_server->getScriptBacktrace();
+			if(!bt.empty())
+				os<<std::endl<<bt;
+			else
+				os<<std::endl<<"No backtrace.";
+			m_server->setAsyncFatalError(os.str());
 		}
 	}
 
@@ -3114,6 +3121,12 @@ Inventory* Server::createDetachedInventory(const std::string &name)
 	return inv;
 }
 
+std::string Server::getScriptBacktrace()
+{
+	MutexAutoLock lock(m_env_mutex);
+	return m_script->getBacktrace();
+}
+
 // actions: time-reversed list
 // Return value: success/failure
 bool Server::rollbackRevertActions(const std::list<RollbackAction> &actions,

src/server.h

@@ -293,6 +293,8 @@ public:
 	// Envlock and conlock should be locked when using scriptapi
 	GameScripting *getScriptIface(){ return m_script; }
 
+	std::string getScriptBacktrace();
+
 	// actions: time-reversed list
 	// Return value: success/failure
 	bool rollbackRevertActions(const std::list<RollbackAction> &actions,